Differential pressure indicator



0d. 21, 9 G. E. BARNHART DIFFERENTIAL PRESSURE INDICATOR Filed March 2, 1940. 2 Sheets-Sheet l INVENTOR. Georqe E. Bar-nl'sarf- ATTORNE 21, 1941- G. E. BARNHART DIFFERENTIAL PRESSURE INDICATQR Filed March 2, 1940 2 Sheets-Sheet 2 a R o m r .n N a n W NE 1 I e 7 7 a w u u m G I 4 v 7 l A m 5 8 a un 1 mm m m w w a @x W m U 4 w w M w M mLm n a u w a u Patented Oct 21, 1941 UNITED STATES PATENT OFFICE DIFFERENTIAL PRESSURE INDICATOR George E. Barnhart, Pasadena, Calif.

Application March 2,1940, Serial No. 321,955

' '1 Claims. (Cl. 200-83) This invention relates to improvements in registering instruments.

The general object of the invention is to provide an improved instrument for registering atmospheric changes.

Another object of my invention is to provide a novel recording instrument including a plurality of hollow expansion members which may be oi. equal volume and which contain gas which may be under diiferent pressures in the respective members and wherein the movement of an indicator is subject to the combined effect of the members.

A further object of the invention is to provide an instrument including expansible and contractable members whose movement is efiected by forces supplied by members connected thereto.

Another object or the invention is to provide an instrument including expansion and contraction members which serve to control a circuit which circuit may include a light means.

A further object of the invention is to provide a balanced pair of expansible and contraotable elements wherein the elements may bethrown out of balance by evaporative means applied to one of, them and wherein, if desired, the elements may serve to control an electric circuit.

An additional object of theinvention is to provide a pair of expansible and contraotable elements which mutually cooperate to control movement of an indicator when one of the elements is subjected to evaporative eilects and wherein the indicator will not move when the instrument is subjected to barometric and temperature changes.

An additional object of the invention is to provide an instrument including a pair of opposed expansible and contraotable members whose movement is effected by forces supplied by other members connected thereto and wherein one of the other members responds to atmospheric changes and the other to humidity changes.

Other objects and the advantages of this invention will be apparent from the following description taken in connection with the accompanying drawings. wherein:

Fig. 1 is a side elevation, partly in section, showing my improved registering instrument;

Fig. 2 is an enlarged fragmentary view similar to Fig. 1 with portions thereof in section;

Fig. 5 is an enlarged section taken on line E5, Fig. 1;

Fig. 6 is a fragmentary view similar to Fig. i with parts thereof in section and showing an evaporative member onone of the bulbs;

Fig. 7 is a fragmentary view similar to Fig. l

with parts thereof in" sectionand showing an taken on line 11-, Fig. 8;

Fig. 12 is a section taken on line 52-62 Fig. .JL; Fig. 13 is a section taken on line tt-it, ii; Fig. 14 is a fragmentary view similar to Fig. 8

showing an evaporative member on one of the Fig. 3 is an enlarged fragmentary section taken expansible and contraotable members; and.

Fig. 15 is an end view of the device shown in Fig. 8 showing an evaporative member on one of. the bulbs.

Referring to the-drawings by reference char- Each of the neck portions 99 has a recess 26' therein to receive the rod l6 which is hermetically sealed thereto by a suitable cement 2 I. Each of the necks I 9 further includes a small aperture 22 opening into the interior of the bulb and into the recess 20 which when the bulb and tube are connected communicates with the tube aperture I1.

Inwardly from the brackets I 3 and i4 each of the tubes is connected to a plurality of interconnected expansibie and contraotable members such as bellows 23.

' Intermediate the bulb and the bellows each of the rods I6 includes a valve member 24 which is shown as of the plug valve type for controlling the passageway through the bore II. The plugs 25 of each of the valves 24 include a stem portion 26 having an operating handle 21 thereon.

Each of the innermost bellows elements 23 ineludes an extended arm 28 having an elongated slot therein. Thetwo arms 28 are positioned within the flanges of a connecting channel mem= her Elli (see Fig. 1) and each of the arms is releasably connected to its associated channel by a bolt 3i positioned in the arm slot 29 and in an aperture in the channel. Each of the arms Ed is to be clamped to the channel 3t by a thumb nut positioned on the bolt iii. A: though both the bulbs 58 and the bellows 2'5 are shown as of equal volume this is by way of illustration only as each may be of a suitable volume while the bulbs and/or bellows may have gases of different pressures therein, and this is preferably the case when the device is set up as shown in. Fig. l. Thuses atmospheric conditions change one set or" bellows will expand thereby contracting the other set, thus moving the channel 3d.

Intermediate the brackets it and it the base includes an upwardly extending support 36 on which a pivot member 35 is mounted. As clearly shown in Fig. 3 the pivot memberi sd includes an inverted ill-shaped portion and a polygonal shank portion N which is positioned. in an elongated aperture 88 in the support The pivot member 35 further includes a reduced threaded stem 38 extending from the shank ill and has a washer 6-3 and a thumb nut ll thereon by which the pivot member 35 is clamped to the support 3%.

The pivot member 35 supports a depending iiidicating arm which adjacent the upper end includes a trunnion member 33 which is pivotally supported in bearing members lid in the pivot member 35.

A predetermined distance below the trunnion the arm 32 has a vertically elongated aperture lli therein in which a pin secured to the charrnel is positioned. Thus when the channel is moved as previously described the arm ll will be swung about the axis of the trunnion 53.

Adjacent the lower end the arm (12 supports a roller member d'l having a vertical axis and a predetermined dise nce thereabove a similar roller member also having a vertical axis.

Mounted on the support 36 adjacent the base l2 I provide a contact plate db which is made of an electrical insulating material. Adjacent each end the plate (it has a polygonal shank iii} secured thereto as by a screw 5i and each of the shanks til includes a reduced threaded stem The shanks so are each positioned in a horizon= tally elongated slot 53 in the support 3 and each of the threaded stems 52 has a washer lid and a thumb nut 55 thereon by means of which the shanks 5d are clamped to the support dd.

Adjacent the roller ll the plate so has a plurality of arcu'ately arranged spaced electri cal contacts 56 thereon and thereabove an arou= ately shaped electrical contact bar Jail.

The contacts lit and the contact bar 52' may be connected to any suitable electrically operated device desired by suitable wires (not shown) which would extend through an aperture b8 (Fig. 3) in the support 8 3.

The roller ll on the arm 52 bridges between the contact bar ill and the contacts lid and to retain the roller in engagement with the contact bar and the contacts I provide an arcuately. shaped bar Fill the ends of which are slidably supported on studs til mounted on the plate 69 (see The studs 60 include enlarged heads til spaced outwardly from the bar so and surrounding each of the studs 683 between the heads iii and the bar.

lid

I provide a coiled spring 32 which resiliently urges the bar 59 towards the roller at which it contacts thereby urging the roller ll into onthe effect ol'the gases within one or both of the bulbs 98 and this may be done by closing one or both of the valves 2 i To cause the device it to react to humidity changes a cloth or other evaporative member to is positioned over one of the bulbs 58 as shown in. Fig. 6; The member has a wick 5d connected thereto which extends into a container 65 having water therein.

The device it will also react to humidity changes by placing an evaporative member over one set of the bellows members 23 as shown in Fig. 7. The member 66 has a wick member bl connected thereto which extends into a container having watertherein.

In this form the device may be used to indicate changes in the humidity of the air. A reduction in humidity of the air will cause increased evaporative cooling of the bulb covered by the evaporative member 53 thereby reducing the gas pressure within this bulb and causing the bellows connected thereto to contract, thus shifting the arm :32.

The evaporative members may be placed on either the bulb E8 or on the bellows members 23 as just described or such members may be placed on both the bulb and bellows members on one side of the device.

in 53 l have indicated a modified form of my invention generally at As shown the device lt includes a base ll having spaced brackets l2 l8 thereon which include bearing port'lons id.

Supported in each of the bearings Ed I provide a rod l5 having a small axial bore l6 there-,

through (see Fig. 4). On the outer portions of each of the rodslii I providea glass orother transparent bulb member it, which includes aneck portion ll.

Each of the neclr portions ill has a recess 18 therein to receive the rod :15 which is hermetically sealed thereto by a suitable cement it. Each connected communicates with the tube aperture inwardly item the brackets each of the rods it has a vertical tube 81] secured thereto, the interlor of which communicates with the bore as through an aperture $2 in the rod it. The open end of a Eourdon tube 88 is secured to the tube 86 and communicates with the interior thereof.

Intermediate the bulbs 36 and the tubes at each of the rods l5 includes a valve member 86 which is shown as of the plug valve type for controlling the passageway through the bore it. The plugs 85 of each of the valve members 8% includes a stem portion so having an operating handle ill thereon.

Intermediate the brackets 32 and l the base H has an upwardly extending support member at thereon which includes two spaced apertured brackets 59 extending therefrom.

Positioned in the brackets it I provide tube 2,259,446 having an elongated aperture 92 therethrough.

Adjacent the aperture 92 the tube 90 has an aperture 03 therein and opposite which the tube 90 has an enlarged aperture 04 therein.

The shank of a bolt is positioned in the aperture 93 and extends through the aperture 92 in the rod 9| and through the enlarged tube aperture 84.

A thumb nut 98 which includes a reduced extended portion 91 is positioned on the bolt 95 with the portion 91 positioned in the tube aperture 00. When the nut 96 is tightened on the bolt the nut portion 01 engages the rod 9| thereby clamping the rod 9i to the tube 90.

The closed ends of each of the Bourdon tubes each of which have an elongated aperture 99 therethrough to receive a pin I00 in the rods 9|.

With the device I0, as with the device I0, each set of bulb and expansible and contractable members may have gases of difierent pressures therein, thus as atmospheric conditions change, one Bourdon tube 83 will expand thereby contracting the other and thus moving the tube 90.

Intermediate the brackets 09 and thereabove a pivot member IOI is'mounted on the support 00. As clearly shown in Fig. 11 the pivot member IOI includes an inverted U-shaped portion I02 and a polygonal shank portion I03 which is positioned in an elongated aperture I04 in the support IN. The pivot member IOI further includes a reduced threaded stem I05 extending from the shank I03 and has a washer I06 and a thumb nut I01 thereon by means of which the pivot member IN is clamped to the support 88.

The pivot member IOI supports a depending U-shaped stirrup I08 each leg of which adjacent the upper end includes a trunnion member I09 which is pivotally supported in a, bearing mem-' ber H0 in the pivot member IN. The outer leg of the stirrup I00 has a vertically elongated aperture II2 therein in which a pin H3 in the tube 90 is positioned. Thus when the tube 90 is moved as previously described the stirrup I08 will be swung about the axis of the trunnions I09.

Mounted in an inverted U-shaped bracket IN on the bottom of the stirrup I08 I provide a reflecting prism H5 above which the bracket has an aperture I I6. I

Supported by the pivot member IN I provide an electric light socket III to receive an electric light bulb II8 the light rays from which pass through the aperture H6 in the bracket Ill and through the prism I II whereby they are directed to one side, thereby multiplying the indicator movement without adding an inertia eflect.

At the side of the device I0 to which the light rays are directed I provide a closed container I in which I show two light sensitive elements such as photo-electric cells I2I. One face of the container I20 has ports I22 therein which direct light rays onto the photo-electric cells.

The container I20 is shown as positioned in a well I23 in the base II and suspended from a threaded shank I 24 which is positioned in a threaded aperture I25 in a bracket portion I26.

- A nut I21 is provided on the shank I24 to lock by placingan evaporation member I3I over one of the bulbs 16 as shown in Fig. 15. The member I3I has a wick member I32 connected thereto which extends into a container I33 having water therein.

The evaporation members may be placed on either one of the bulbs or on one of the Bourdon tubes as just described or the members may be placed on both the bulb and Bourdon tube on.

one side of the device.

Having thus described my invention, I claim:

1. In a device of the class described, a base having a pair of axially aligned hollow rods supported thereon, a bulb member connected to each of said rods and communicating therewith, means for controlling passage of fluid through each rod, a hollow expansion and contraction member mounted on each rod and communicating with the interior of the rod, means connecting thv expansion and contraction members, a support on the base, an indicating arm movably mounted on said support, means operable by said connecting means for shifting said indicating arm, a plurality of spaced contact members on the support and a circuit closer on said indicating arm and movable to engage the spaced contact members.

2. In a device of the class described, a base having a pair oi axially aligned hollow rods supported thereon, a bulb member connected to each of'said rods and communicating therewith, means for controlling passage of fluid through each rod, a hollow expansion and contraction member mounted on each rod and communicating with the interior of the rod, a connecting member, means securing the connecting member to each expansion and contraction member, a support on the base. an indicating arm pivotally mounted on said support, means whereby when said connecting member is shifted-said indicating arm is moved, a plurality of spaced contact members on the support, a circuit closer on said indicating arm and movable to engage the spaced contact members, and means to urge the circuit closer towards the contact members.

3. In a device of the class described, a base having a pair of axially aligned hollow rods supported thereon, a bulb member connected to each of said rods and communicating therewith,

means for controlling passage of fluid through each rod,an expansion and contraction member -mounted on each rod and communicating with the interior of the rod, a connecting member, means securing the connecting member to each expansion and contraction member, a support on the base, an indicating arm pivotally mounted on said support, means whereby when said connecting member is shifted said indicating arm is moved, a plurality of spaced contact members on the support, a circuit closer on said indicating arm and movable to engage the spaced contact members, and means to urge the circuit closer towards the contact members.

4. In a device of the class described, a base having a pairof axially aligned hollow rods supported thereon, a bulb member connected to means for controlling passage of fluid through each rod, an expansion and mounted on each rod the interior of the rod, a connecting member, means securing the connecting member to each expansion and contraction member, a support on the-base, an indicating arm pivotally mounted on said support, means whereby when said connecting member is shifted said indicating contraction member and communicating with is moved, an insulated contact plate on the support, an. eloug'ated contact member on the plate, spaced contact members on the plate, a circuit closer on said indicating arm and movable with the arm in engagement with the elou= gated contact member and adapted to engage thespaced contact members in order, and means to urge the circuit closertowarcisthe contact members.

5. In a device of the class described, a base having spaced brackets thereon, a hollow rod supported on each bracket, said rod being axially aligned, a bulb member connected to each of said rods and; communicating therewith, valve means for coutroiling passage of fluid through each rod, an expansion and contraction member mounted on each rod and communicating with the interior of rod, an arm connected to each expansiori'anci contraction member, a conmeeting member, adjustable means securing the connecting member to each arm, a support on the base, an indicating arm pivctaliv mounted on said supeort, means whereby when said con necting member is shifted said indicating arm is moved, an insulated contact plate on the support, an elongated contact member on the plate, spaced contact members on the plate, a roller mounted oh said indicating arm and movable with the arm in engagement with the elongated contact member and adapted to engage the spaced contact members, and means to urge the roller towards the contact members.

6. hi a device of the class described, a ease having spaced brackets thereon, a hollow rod supported on each bracket, said rod being; asiallv aligned, a bulb member having a neck hermeticaily connected to each of said rods and communicating therewith, a valve on each hollow rocl remote irom the bulb and controlling passage or" fluid through the associated rod, an

expaesiou and contraction member mounted on each rod and comprising a plurality oi elements communicating with the interior of the rod, an arm connected to each expansion and contraction member, a connecting member, slotted means for relewaloiy and adjustahly securing the connecting member to each of said arms, a sup port on the base, a shiitahle pivot on said S1lp= accuses port, an indicating arm on the pivot, meats whereby when said connecting member is shiit= ed said indicating arm is moved, an insulated contact plate shiitahly mounted on the supaoit, an elongated contact member on the plate, spaced contact members on the plate, a roller mounted on said indicating arm and movable with the arm in engagement with the, elongated contact member and adapted to engage the spaced contact members, and resilient means urging the roller towards the contact meuileet 7. In a device of the class described, a hose having spaced brackets thereon, a hollow rod supported on each bracket, said rods ially aligned, a bulb member having a heel: her tactically connected to each of said rode sud communicating therewith, a valve on each hol low rod remote from the and coutsoiiiue; passage of fluid through the associated rod, an expansion and couti'action member mounted on each rod and comprising a plurality of elements communicating with the interior of the red, an arm connected to each expansion and contraction member, a connecting member, slotted means for releasably and adjustable securing the connecting member to each of said arms, a sup-- port on said base, an indicating arm, a pivotal mounting for said arm, means to shifta'bly sup port the pivotal mounting on the support,- means whereby when said connecting member is shitted said indicating arm is moved, an insulated contact plate, means to siuitebly mount the plate on the context, an elongated contact mem her on the plate, spaced contact members on the plate, a roller mounted on said indicating arm and movable with the arm in engagement with the elongated contact member and adapted to engage the spaced Contact members in order, a second roller on said indicating arm and resiii= ent shiftable means engaging said second roller to urge the indicating arm so that the first rcilei thereon engages the contact memhers, each huih and each expansion and contraction member communicating with the receptacles and seine adapted to he engaged by an evaporative aiem= ber.

GEQRGE E. 

